Cyclic esters are useful compounds that can be polymerized into polymeric materials. Such polymeric materials are useful in the preparation of biodegradable plastic materials and other plastic materials. Cyclic esters are also useful as plasticizers and as intermediates for production of surface-active agents and plasticizers.
Cyclic esters are usually prepared by condensing hydroxy acids to an oligomeric prepolymer. The prepolymer is then depolymerized to a cyclic ester. The production of a cyclic ester from an oligomeric prepolymer is sometimes referred to as a back-biting reaction. The back-biting reaction is typically a slow one, and a batch operation which extends over significant time and which results in undesirable byproducts. Extensive purification processes are therefore required to obtain cyclic esters of requisite purity.
Therefore, there remains a need for processes for preparing cyclic esters that overcome one or more of the aforementioned issues. It is an object of the present invention to provide a process for preparing cyclic esters and cyclic amides.